A variable neighborhood search method for generalized blockmodeling of two-mode binary matrices

The clustering of two-mode proximity matrices is a challenging combinatorial optimization problem that has important applications in the quantitative social sciences. We focus on one particular type of problem related to the clustering of a two-mode binary matrix, which is relevant to the establishment of generalized blockmodels for social networks. In this context, clusters for the rows of the two-mode matrix intersect with clusters of the columns to form blocks, which should ideally be either complete (all 1s) or null (all 0s). A new procedure based on variable neighborhood search is presented and compared to an existing two-mode K-means clustering algorithm. The new procedure generally provided slightly greater explained variation; however, both methods yielded exceptional recovery of cluster structure.     

Use of the high-probability instructional sequence and escape extinction in a child with food refusal

We used the high-probability (high-p) instructional sequence with and without escape extinction in the treatment of food refusal. Acceptance increased and refusal decreased only with the introduction of escape extinction. These results raise important questions about the high-p sequence in the treatment of food refusal.     

A two-stage logistic regression model for analyzing inter-rater agreement

Studies of agreement commonly occur in psychiatric research. For example, researchers are often interested in the agreement among radiologists in their review of brain scans of elderly patients with dementia or in the agreement among multiple informant reports of psychopathology in children. In this paper, we consider the agreement between two raters when rating a dichotomous outcome (e.g., presence or absence of psychopathology). In particular, we consider logistic regression models that allow agreement to depend on both rater- and subject-level covariates. Logistic regression has been proposed as a simple method for identifying covariates that are predictive of agreement (Coughlin et al., 1992). However, this approach is problematic since it does not take account of agreement due to chance alone. As a result, a spurious association between the probability (or odds) of agreement and a covariate could arise due entirely to chance agreement. That is, if the prevalence of the dichotomous outcome varies among subgroups of the population, then covariates that identify the subgroups may appear to be predictive of agreement. In this paper we propose a modification to the standard logistic regression model in order to take proper account of chance agreement. An attractive feature of the proposed method is that it can be easily implemented using existing statistical software for logistic regression. The proposed method is motivated by data from the Connecticut Child Study (Zahner et al., 1992) on the agreement among parent and teacher reports of psychopathology in children. In this study, parents and teachers provide dichotomous assessments of a child's psychopathology and it is of interest to examine whether agreement among the parent and teacher reports is related to the age and gender of the child and to the time elapsed between parent and teacher assessments of the child.The authors thank the Associate Editor and the referees for their helpful comments and suggestions. We also thank Gwen Zahner for use of data from the Connecticut Child Study, which was conducted under contract to the Connecticut Department of Children and Youth Services. This research was supported by grants HL 69800, AHRQ 10871, HL52329, HL61769, GM 29745, MH 54693 and MH 17119 from the National Institutes of Health.     

Hierarchical classes models for three-way three-mode binary data: interrelations and model selection

Several hierarchical classes models can be considered for the modeling of three-way three-mode binary data, including the INDCLAS model (Leenen, Van Mechelen, De Boeck, and Rosenberg, 1999), the Tucker3-HICLAS model (Ceulemans, Van Mechelen, and Leenen, 2003), the Tucker2-HICLAS model (Ceulemans and Van Mechelen, 2004), and the Tucker1-HICLAS model that is introduced in this paper. Two questions then may be raised: (1) how are these models interrelated, and (2) given a specific data set, which of these models should be selected, and in which rank? In the present paper, we deal with these questions by (1) showing that the distinct hierarchical classes models for three-way three-mode binary data can be organized into a partially ordered hierarchy, and (2) by presenting model selection strategies based on extensions of the well-known scree test and on the Akaike information criterion. The latter strategies are evaluated by means of an extensive simulation study and are illustrated with an application to interpersonal emotion data. Finally, the presented hierarchy and model selection strategies are related to corresponding work by Kiers (1991) for principal component models for three-way three-mode real-valued data.     

Verbal Implicit Sequence Learning in Persons Who Stutter and Persons With Parkinson's Disease

The authors investigated the integrity of implicit learning systems in 14 persons with Parkinson's disease (PPD), 14 persons who stutter (PWS), and 14 control participants. In a 120-min session participants completed a verbal serial reaction time task, naming aloud 4 syllables in response to 4 visual stimuli. Unbeknownst to participants, the syllables formed a repeating 8-item sequence. PWS and PPD demonstrated slower reaction times for early but not late learning trials relative to controls reflecting delays but not deficiencies in general learning. PPD also demonstrated less accuracy in general learning relative to controls. All groups demonstrated similar limited explicit sequence knowledge. Both PWS and PPD demonstrated significantly less implicit sequence learning relative to controls, suggesting that stuttering may be associated with compromised functional integrity of the cortico-striato-thalamo-cortical loop.     

Effector Independence

Although effector independence is predicted in a number of theoretical perspectives, it has received only moderate empirical support. The authors conducted 3 experiments to determine the extent to which simple motor sequences are effector independent. A measurement scheme that partitioned response errors into independent error measures attributable to the relative structure of the response and the force-time scaling of that structure was used in the analysis of the present experiments. The results indicated that the relative structure of the response could be effectively transferred from one limb to the contralateral limb (Experiment 1), to a different muscle group on the same limb (Experiment 2), and from a static to a dynamic version of the task (Experiment 3). The ability to scale force was effector dependent, however, and the force scaling was relatively ineffective when an unpracticed limb was used. Although participants (Ns = 20, 24, and 20, respectively, in Experiments 1, 2, and 3) were effective in transferring the movement structure from a static to a dynamic version of the task, they were not very effective in transferring from a dynamic to a static version of the task. The transfer difference appeared to be related to the information that was available to support performance of the dynamic version of the task, which was not available in producing the static version.     

Acquisition of Effector-Specific and Effector-Independent Components of Sequencing Skill

In a serial reaction time task, participants practiced a repeating sequence with 1 hand. In interleaved blocks, they responded to random sequences with the other hand. Experiment 1 was composed of 5 sessions, each consisting of 30 blocks. Intermanual transfer, reflecting a hand-independent component of sequence knowledge, increased across session. A smaller but significant, nontransferable, and hand-specific component was evident in each session and did not increase with practice. Experiment 2 comprised only 1 session. Uninterrupted practice (no interleaved random blocks) improved hand-independent sequence learning in comparison with interrupted practice (as implemented in Experiment 1), whereas hand-specific sequence learning was unaffected by this between-subjects manipulation. These findings suggest separate mechanisms for effector-independent sequence learning and effector-specific acquisition of optimized response coarticulation.     

A Data Analysis Method for Using Longitudinal Binary Outcome Data from a SMART to Compare Adaptive Interventions

Sequential multiple assignment randomized trials (SMARTs) are a useful and increasingly popular approach for gathering information to inform the construction of adaptive interventions to treat psychological and behavioral health conditions. Until recently, analysis methods for data from SMART designs considered only a single measurement of the outcome of interest when comparing the efficacy of adaptive interventions. Lu et al. proposed a method for considering repeated outcome measurements to incorporate information about the longitudinal trajectory of change. While their proposed method can be applied to many kinds of outcome variables, they focused mainly on linear models for normally distributed outcomes. Practical guidelines and extensions are required to implement this methodology with other types of repeated outcome measures common in behavioral research. In this article, we discuss implementation of this method with repeated binary outcomes. We explain how to compare adaptive interventions in terms of various summaries of repeated binary outcome measures, including average outcome (area under the curve) and delayed effects. The method is illustrated using an empirical example from a SMART study to develop an adaptive intervention for engaging alcohol- and cocaine-dependent patients in treatment. Monte Carlo simulations are provided to demonstrate the good performance of the proposed technique.     

First steps in developing the Dutch version of the Bayley III: Is the original Bayley III and its item sequence also adequate for Dutch children?

The Bayley Scales of Infant and Toddler Development [Bayley III, Bayley, N. (2006). The Bayley scales of infant and toddler development. San Antonio, TX: The Psychological Corporation] is currently developed and exclusively normed for American children. In this study, the appropriateness of the Bayley III item content and item sequence for Dutch children was evaluated. The translated version, the Bayley-III-NL was evaluated in two phases. In phase 1 (N = 100), analyses showed that overall the item content seemed to be appropriate for Dutch children. In addition, the item sequence was found to be suitable for Dutch children. After phase 1, small adaptations were made to the instructions of a few items based on the experiences of the examiners to improve standardization in performance. In phase 2 (N = 400), the findings of phase 1 were confirmed in a larger sample. It is concluded that Dutch norms can be based upon the current version of the Bayley-III-NL.     

Motor Programming When Sequencing Multiple Elements of the Same Duration

Motor programming at the self-select paradigm was adopted in 2 experiments to examine the processing demands of independent processes. One process (INT) is responsible for organizing the internal features of the individual elements in a movement (e.g., response duration). The 2nd process (SEQ) is responsible for placing the elements into the proper serial order before execution. Participants in Experiment 1 performed tasks involving 1 key press or sequences of 4 key presses of the same duration. Implementing INT and SEQ was more time consuming for key-pressing sequences than for single key-press tasks. Experiment 2 examined whether the INT costs resulting from the increase in sequence length observed in Experiment 1 resulted from independent planning of each sequence element or via a separate "multiplier" process that handled repetitions of elements of the same duration. Findings from Experiment 2, in which participants performed single key presses or double or triple key sequences of the same duration, suggested that INT is involved with the independent organization of each element contained in the sequence. Researchers offer an elaboration of the 2-process account of motor programming to incorporate the present findings and the findings from other recent sequence-learning research.